The addictions nurse admits patients to the facility. She assesses the patient, at admission and throughout care, both for general illness and for symptoms of withdrawal. She medicates according to doctors' orders. She evaluates effectiveness of medications. She facilitates groups, both educational and psychological, delegates to the others working with her, who aren't nurses, talks to doctors, social workers, other therapists, and fills out tons of paperwork.
Where I work we utilize both LPN's and RN's. LPN's duties- first half of new admissions, perform breathalizer/urine drug screen tests, vital signs and CIWA/CINAS, medication administration, work with RN and run a therapeutic group. RN duties- chart on every patient, do 2nd half of admissions and assessment of Pt, help run group with LPN, deals with insurance companies.